U.S. Pat. No. 4,355,298 describes a system to give a warning of a low or flat tire condition to an aircraft crew in the cockpit of the aircraft. The system is able to produce distinct warning signals for more than one distinct dangerous tire condition. For example, it may be desired to produce one warning signal when a tire is only slightly under inflated and to produce a second warning signal when the same tire is greatly under inflated.
U.S. Pat. No. 4,283,707 describes an aircraft low tire pressure sensing and cockpit display and warning system utilizing axle wheel pair comparator circuitry.
A problem with the system of U.S. Pat. No. 4,355,298, and other similar conventional low or flat tire warning systems, is that when the aircraft is in motion a low tire pressure warning signal may be issued even though the pressure of the tire is still sufficiently high for the aircraft to be operated safely. In this case the warning signal is unnecessary and may distract the aircraft crew. It may also prompt the aircraft crew to abort the flight even though the aircraft can still be operated safely.